1. Field of the Invention
The present invention relates to an image recognition device for performing recognition processes to detect presence of a target object.
2. Description of the Related Art
In a conventional image recognition device, in order to speed up its recognition processes by skipping pixels in image data, the number of pixels skipped in the recognition processes, which is referred to as the skipping distance hereinafter, is configured in accordance with the size of a recognition target, and an image in a recognition area has been scanned with the configured skipping distance (see, for instance, Japanese Patent Laid-Open No. 99724/2000 (FIG. 2)).
In addition, in the conventional image recognition device, in order to enhance detection-accuracy tolerance to luminance variations, a normalization process such as luminance tone adjustment is performed on the whole image or the recognition area within the image data. In order to calculate parameters for the normalization process, feature quantities such as pixel values of the whole image or in the recognition area are obtained. It then corrects the pixel values by using a look-up table or an equation that represents a luminance tone-curve.
In the conventional image recognition device, once the skipping distance has been set, it remains fixed intact. Therefore, a problem has been that cases may occur in which a recognition target cannot be found when the recognition target is present within the skipping distance.
Another problem of the conventional image recognition device has been that an algorithm used in the normalization process that corrects pixel values of the whole image or in the recognition area is fixed, and the amount of computations cannot be neglected when the number of pixels increases.